Fuse



L E9@ L. K. LHLJEGREN FUSE Filed Sept. l, 1944 l 4 The invention described herein `facturedand used by or for theGovernment for Patented ug. 1, 1950 FUSE a Lyle L`K.Liljegren, Silver Spring, Md., assignor to the United States of America as represented by s the'Secretary of War old may be manugover'nmental purposes without the payment to "me` of any royalty thereon.

` Myinventionrelates to `fuzesA and particularly to pressure fuzes.

LThe present fuze 1s adaptable for many uses `especially advantageous in explosive devices lused in connection with booby trap installations where' actuations by pressure are desired, and in 10 mine fields where numerous tanks or the like may enter the eld'a predetermined distance without harm or effectbefore the charges are set off.

`Ordinarily, a mine is exploded by the first contact 222 therewith thereby warning the following tanks of ka dangerous condition ahead. 4In the instant case 'means are' provided whereby numerous tanks may be caught in a trap since a predetermined number of `contacts for actations arenecessary before the f mine is nally exploded. It is therefore a primary object of my invention to provide a repeated Aimpnlsetype fuze which can be set to function an f `Figure 1 isa side sectional View of my improved 50 4uze, l a j f "Figure 2 isa section taken on the lm ewz-z'pf rFignlg" i. y i i yexplosivecharge' after thel actuating means has `been subjected to a number of impulsesY for which i"" thefuze was set. l

' ,Another object is `to provide a fuze having a conventionalscrew threaded base plugv or deto- 'nator holder for tting a land mine, booby trap,

,4 grenade and the like which willV safely permit a predetermined number of actuations and will not berendered eifectivetoexplode a charge until a set number of impulses have been received.l

i A 'further object is toiprovide'a fuze with an` impulse receiverl whereinfsame is set from its in-' terior, the number of impulses for which it is set beingl not visible from its exterior.

A still further object is to provide novel cou- `pligfand releasing meansffor the ring pin or*v` striker.. Y a l, "a vStill another objectis'to provide a simple, coin- 40 l pact and `fool-prooi structure for `iiring an explosi've charge at a predetermined time and one "lwhic'his lconstructed 'to withstand the elements',

Other "objects and advantages will be apparentm `from',thefollowing description, reference being 45 had Ato thefaccompanying rdrawings"forming a part of this application and in which like numer- Yals designate like parts in all views.

In the drawings,

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Application September 1, 1944, Serial No. 552,351

' 7 claims. (011102470) v(Granted under the act of March 3, 1883, as

`amended. April 30,.1928; 370 O. G.f757) Referring to the drawing, IIJ designates the `housing or casing of the fuze which is provided with vertical and horizontal bores II and I2 respectively. Apertures I2 are provided in the base yI3 of the body Il) to fasten the fuze to a support if desirable. A pressure element or impulse receiver is indicated at I4, and this element comprises a button or cap I5 and a resistance spring I6` which serves to urge the button outwardly. Retaining flanges I'I and II' are provided to limit thevertical movement of the cap and are engaged *by the cap fingers I5. As will be appreciated this member I5 is operated by the weight or impulse of any object which passes thereover wherein the pressure on the cap overcomes the resistance of the spring. This movement provides the impulse means for operating the ring pin or striker arranged in the fuze since each time thecap is depressed one actuation or impulse is provided.

A substantially U-shaped pawl I8 is located in the vertical bore I I and xed to the cap I5 in any suitable manner and operates a ratchet nut I9 arranged in a reduced portion II of the bore II when pressure on the cap is provided. This member I9 is provided with ratchet teeth 20 and is threaded on anon-rotatable screw or shaft 2I longitudinally arranged in the horizontal bore I 2. As pressure is applied to the impulse receiver I4 the cap I5 forces the pawl down to engage a tooth 20 whereby the nut I9 is advanced one step or Ynotch in a clockwise direction as observed in Fig. 2.` Since the nut isthreaded on the screw rod 2| and sincethe screw cannot rotate, the turning of the nut I0 causes the screw to back away from coupling engagement with a iiring pin or striker 22 carried on its end.

The screw may be adjusted or set for any number of turns of the nut I9 before it frees the substantially U-shaped spring firing pin 22 which is provided with-the firing head- 22. Screw 2I is provided with' an extension 24 having longitudinally extending channels or abutments 23 thereinA adapted to receive or seat the spring arms 32,

33 on the firing pin 22. `The arms of the pin are provided with offsets or lugs 25 to seat in the two openings or abutments 26 formed by drilling a vertical bore'through the fuze body at the position indicated. It will be noted that since the `armsofthe striker seat in these two openings 2E in the fuze body, the striker is prevented from rotation while the arms remain separated byremaining `in the channels or grooves 23 of the screw extension, and necessarily prevent the screw from rotating since the arms slide in the grooves in the 5 screw extension. Since the screw cannot rotate. 'the clockwisefrotation of the nut I9 as seen in Fig. 2 necessarily causes the screw to move in a longitudinal direction backing away from engage- `simple means of operating the fuze. y `onthe impulse receiver overcomes resistance of ment with the striker 28. In this manner, successive stepby stepactuations will 'iinally cause the screw to bec'orhe entirely disengaged from thering pin means. Since contact with the extension rod 24 holds the spring arms open and the lugs;

25 in the retaining bores 26 a release of the striker from the rod causes the retraction o f the spring arms and disengagement of 'the lilgsroh the re-y taining bores 26 and perriiitsthe' iring' pin tol -rifed by the pin 22.

The travel length ofthe screw is to be adjusted Vfrom the interior of the fuze as to the desired number of impulses or actuations itis to receive before the r-ing pin is disengaged therefrom. If desirable, the screw may be marked in any 4suitable manner to indicate the number of impulses or actuations necessary to release the firing pin at ra. certain .given point thereon; For` this purpose the -fuze is provided with a removable screw threaded A casing y35 whereby the working vparts may be readily reached. A travel space v34 is also provided to receive the screw end `as it is being set or uncoupled.

II-he pawl and ratchet assembly provides fa Pressure the cap spring whereby the ratchet thru the me.-

d-ium ofthe pawl is givena turn-and altera pre- Idelayedvmeans of :operation is especially desir- -la'bl'e =in warfare vand can be .particularly destructive since the presence of a mlineror trap is yoverlooked after a limitednumber of contacts or vpassages have been made thereover and no damage has occurred. Howevera` upon a certain ,pre-

determined contact the mine or trap is explodedv and the result may be more devastating.

It willthus vbe seen 4that -1- vhave developed a uze which is simple, eectivef,-'and one kvvhic-h `is Iable to ulithstand various weather conditions.

When in position the impulse :receiver-is fpreferably placed just beneath the' surface of -the ground or otherwise camouflaged Iand' objects 'r'naypass thereover a predeterminedv number of times without `danger before the firing pin or striker is operable to setoi :a charge. yIt will be Iappreciated that each time an object passes thereover one impulse or'aotuation is given the fuzep If the fuze isset for say -20 impulses be- 'iore exploding the char-ge the -device may be l"rendered harmless 'for 19 impulses. but `on the 19th impulse'the striker 4is ready to be released on the nextor ZOthVmpulse whereby the'charge is exploded. The ffuze may be setto-receive any number of impluses from 'i1 up torsayuormore by the weight of a man, or light weight vehicles,

or the spring .resistance may befw'eak and operable by any' light weight contact. W

To set the' fu'ze, the easing 35 is' uhscrewed and the cap I5, pawl I8 and spring I6 are removed from the body I0. If the firing pin 22 vhas not been assembled to the screw 2 I, then the latter must be threaded all the Way through the ratchet IS so litllsthe space 34, and this is done by holding 'the ratchet stationary while the screw 2`I` turned in a', clockwise direction, moving it throughthe ratchet I9. The spring 21 is then placed over the ring pin .22 land compressed 'siuehtly to place the two projections 25 on the firing ,pin opposite #and between the two holes C25 in= the iuie body. The grooves 23 of the screw extension 24 are brought into engagement with the open ends of thering pin 22 so vthat the Vseparation of the ril'ig'J ariii's -32 and' `33 causesithe lugs T25 to become engaged with the Vholes 2li. Turning the ratchet nut I9' then moves the screw extension 24 u'p 'further 'between vthe yarms or forks 3'2 and 3'3 of 'the "flring' pin. These are graduated to indicate' the number of turns required to cause the fuze 'to release. the pin. The ratchet `I-'9is turnedv until the end of the screw extension aligns 'itself with the desiredrgfraduation. The casing 35"is then 'screwed intoy place andthe cap I5, pawl' l'and spring f6 replaced. ,The .fuze is'A new ready tol/'function las describedherein. Where an entirely assembled fuze is to be set, the casing 35' 'and the cap I5, .pawl I8'` and :spring `"I'IS are removed', and" the ratchet Isrotated in the properdirectifo'n"t'.align 'the end or", the .screw extension 24' with the 'de'- sired graduation on the lining Din ffcln'k.l The removed parts-are 'then replaced' and the"`"fu2e is ready .to function.

.-1.` ,A .fuze comprising la casing' having vertical and-longitudinal bores", a depres's'ible member, a pawl mouritedlin said vertical bore and operable `bysaid=-depressible member, a screw mounted in said longitudinal bore, a ratchet nut .mounted on :said screw .for engagemei'itv with' sai'd pawl,

' said screw provided `with .an extension having longitudinally `arranged `channels, .a .spring r'ing piniof substantially 'U-sl'iar'iedv clgfatidn mounted on .one l`end fo'f saidextenson, the legs `of said ,pin engaging vsaid channels, means-'for holding .saiclspink in .locked .position .on said shait, *andV` means whereby saidvfiring ,pin Aur'ilo'c'ked to explode a charge v when ,afpredetemieddiumber or movements have Abeen ,given-libe screw'.

2. In @delayed action ruze, .-a casing, .a .screw mounted in said casing and having a'longitudi- .nally -.exi',ending` first abutment extending .Tf-rom oneend, aJflring-pin adjacent-said .one rendyspring means-.urging fsaidxpin .into charge-.detonating movement, f a spring arm-,carried `by .said f pinlanil -isimultaneously engaging :said .abutment and a second labutmentonsaid casing Lto .thereby `preventirotati'on :of .said [screw .as .well as' chargedetonating movementof said ,pimanl means .'rsponsive to vdiscrete impulses exteioly f said casing for axially 'translating saidl .screwaway fromrsaidv'spring armin .step-by-step mdienient, whereby said spring arm'is 'releases froirhoth Asaid abutments by the .final one of a series ofsai'd impulses.

i 3. i contact kfuze comprising a casing", fa threaded shaft axially "translatable in 'saidV casing, a iirst .abutment on .rand extending .frbm one end of said shaftiogitudinauy therefore second .abutment y.on .said casing, .a .flriii'gpin movable 'in 'said casing, resilitmeans urging said pin into charge-detonating movement, a spring arm carried by said pin and having means engaging both said abutments to thereby prevent rotation of said shaft and movement of said pin, said arm being yieldingly urged into contact with said shaft, and means responsive to discrete contact pressures exteriorly of said casing to retract said shaft step-by-step from said arm whereby said arm and pin are freed from said abutments for charge-detonating movement by the final one of a predetermined number of said pressures. A

4. In a contact fuze, a casing, a threaded shaft mounted in said casing for longitudinal Y movement, said shaft having a pair of diametrically opposed channels extending longitudinally from one end thereof, a firing pin mounted in said casing adjacent said one end for movement longitudinally of said shaft, spring means urging said pin into charge-detonating movement away from said shaft, said pin including a pair of arms having their ends urged toward each other, the end of each arm being simultaneously engaged in a respective channel and in a recess in said casing, whereby to simultaneously prevent rotation of said shaft and movement of said pin, a ratchet nut threaded on said shaft, and spring-pressed pawl means carried Aby said casing and responsive to discrete externall pressures thereon for rotating said nut stepbyj-step to thereby retract said shaft from said pin, whereby said arms are freed from said channels and recesses by the final one only of a predetermined number oi said pressures.

5. In a fu `ze, a casing having a bore, a shaft mounted in said bore for axial translation and having key means extending longitudinally from one end thereof, a ring pin, means mounting said firing pin for firing movement in one direction coaxially with and away from said one end of said shaft, an arm fixed with said ring pin and having lug means remote from said pin to simultaneously engage said key means and an abutment fixed with said casing, said key means and abutment coasting to prevent firing movement of said pin and rotation of said shaft; said arm being resilient to tend to move its lug means radially inwardly out of contact with said abutment, spring means urging said pin into lring movement. and actuating means carried by said casing and engageable externally thereof to move said shaft axially step-by-step away from said lug means whereby said lug means is released from said key means in response to the final one of a predetermined number of actuations of said actuating means to thereby free said firing pin for firing movement.

6. A fuze comprising a spring-pressed member, a pawl operable by said member, a ratchet operable by said pawl, a longitudinally arranged screw, said ratchet being threadedly engaged with said screw to impart a step-by-step longitudinal movement thereto, a firing pin coupled to said screw and restraining the same against rotation, means responsive to the iinal one of a predetermined number of movements of said screw for uncoupling said pin from said screw, a casing for enclosing said screw, said screw having longitudinal channels therein and said firing pin being provided with spring legs to simultaneously engage said channels and said casing to thereby prevent rotation of said screw.

7. A fuze comprising a body having intersecting vertical and longitudinal bores, a depressible member, a pawl reciprocably mounted in said vertical bore and operable in response to actuation of said depressible member, a screw mounted for axial movement in said longitudinal bore, a nut threaded on said screw and mounted for rotation only in said body, said nut being rotatable step-by-step in response to discrete operations of said pawl, a firing pin, means fixed to said pin and engageable with said screw and body to simultaneously prevent rotation of said screw and firing movement of said pin, said screw being axially withdrawn from said means to release said firing pin for iiring movement, only in response to the iinal one of a predetermined number of thrusts on said depressible member.

LYLE K. I .ILJEGREN REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,288,797 Asbury Dec. 24, 1918 1,346,177 Chanard July 13, 1920 1,430,161 Elia Sept. 26, 1922 FOREIGN PATENTS Number Country Date 541,624 Great Britain Dec. 4, 1941 

